Image capture devices, such as digital cameras and other similar mechanisms, are becoming more commonplace. Once available only on high-end professional cameras, today such devices are found in mobile telephones, personal digital assistants, and other portable electronic devices. The image capture devices available in many portable electronic devices include an auto-focus feature. Auto-focus systems use image-processing circuits to automatically determine the proper focus, thereby eliminating the need for the user to do so.
One drawback with such auto-focus mechanisms is that they can be relatively slow. For instance, in some image capture systems integrated into electronic devices (e.g. portable electronic devices such as mobile phones, or stationary electronic devices such as a monitoring camera connected to a network), the auto-focus system must, through intelligent trial and error, move the lens to a particular position that corresponds to a focused image. The auto-focus system does this by examining an image, moving the lens, capturing another image, and examining it again to determine if the proper focus has been achieved. The process is repeated until the optimal lens position is found. The time can be greatly extended if the image capture device is moving when the auto-focus operation is taking place. For instance, a user's shaky hand or a moving platform can cause the image capture device to move significantly. Such movement can result in blurry images, as the autofocus feature lacks a consistent subject upon which to achieve focus. Further, even where focus is finally achieved, such movement causes the auto-focus operation to take even more time to complete.
U.S. Pat. No. 8,274,596 (Motorola Mobility LLC) relates to a method and image capture device for determining whether an image incident upon an image sensor is sufficiently stable prior to executing an auto-focus (AF) process. Whether the image is stable or not can be determined e.g. by hardware such as a gyro or accelerometer. Even if the disclosure in this document may solve the issue of blurry images, since the AF process is not performed unless the image is stable, it does not increase the speed of the AF process. On the contrary, when the camera is moving, the AF process is delayed.